In the field of laboratory animal management, specifically that of small animals such as rats or guinea pigs, use is made of cages which must be kept in predetermined conditions, and generally with different degrees of isolation from the external environment, in order to prevent contaminations of the animals by the external environment and/or contamination of the environment and humans by the animals, if this event represents a danger. Use is made of cages which may be equipped with sealed closure, for example with a lid and a seal which may be provided on the lid or on the cage to make the coupling airtight. There are various lid fastening systems and may include brackets and hooks. The cages are generally provided with means for connecting to a ventilation system, for introducing filtered, decontaminated air and/or collecting air aspirated from the cages for the subsequent filtering and decontamination operations. The ventilation system provides for tubes generally on the racks on which the cages are positioned, with couplings adapted to couple with corresponding couplings provided on the cages when these are arranged in position on the rack. The cages have valves adapted to close when the cage is removed, to separate the inside from the outside. Similar systems are well known; a cage of the type indicated above is described, for example, in patent EP 1 719 406. The cages are provided with side guides to be inserted and supported by corresponding guides of the rack.
The cages must be periodically changed, moving the animals from a dirty cage to a clean one with a certain frequency and positioning the new cages on the rack.
This is performed manually. A possible procedure is as follows: the operator takes a cage in use from the rack, puts it on a working top, or better in a protected structure, for example a laminar flow changing cabin which, in virtue of appropriate air flows, prevents the contamination of cage interiors and of humans when the cages are opened. The operator also puts a clean cage on the top and opens the cages being careful not to touch the inside of the lids and to place the lids upside down on the working top; in order to avoid the contamination, the lids must also be positioned in zones not invested, for example, by the barrier air flow, which is possibly contaminated external air. At this point, the operator disinfects his or her hands, moves the animals, and then closes the cages and puts them onto the corresponding racks. Furthermore, before opening the cage, the drinking bottle must be removed and reintroduced in the new cage, if the type of cage makes the bottle accessible from the outside for being introduced or removed, as in the cages described for example in EP 1 719 406.
It is easy to understand that an operation of such type, repeated on large numbers of cages, implies long times, greatly depending on the operator's ability and on his or her psychophysical condition. There are many possibilities of making errors with a possible contamination of the animals, and of the environment outside and inside the cages, and the fatigue that derives therefrom is quite considerable for the operator, to the extent that many operators complain of cramps or similar disorders, or may even suffer personal injury, which may be translated into forced leave of absence following the physical fatigue. The problems may be worsened by the fact that a seal is interposed between the cage and the lid, which can cause sticking phenomena and a little difference of pressure may occur between the outside and the inside, which may increasingly complicate a repetitive, fluid operation.
The above-described problems have now been solved by an apparatus for changing laboratory animal cages having a lid, the apparatus including at least one seat, preferably at least two seats, each of which for receiving a cage having a lid; the seat being provided with means for picking and lifting the lid.
According to a possible aspect of the invention, devices for detecting the presence of cages in the seat(s) may be provided.
Preferably, the detecting means may be part of a system for enabling the operation of the lid lifting means, system which may alternatively or additionally include other elements, such as enabling devices actuated by the operator.
According to a preferred aspect, the picking and lifting means may also be used for repositioning the lids on the cage.
Preferably, the seat is adapted to withhold the cage in position when lifting the lid, and specifically has means adapted to prevent the lifting of the cage along with the lid.
Preferably, the apparatus is adapted to be used with cages having a removable lid, preferably adapted to be sealed onto the cage and with a locking and releasing mechanism of the lid. The apparatus preferably include means for unlocking the aforesaid mechanism.
The seats may be more than two; according to a particularly preferred aspect of the invention, there are four seats.
The invention further relates to a corresponding method for changing cages.
The apparatus, despite being designed for changing cages, is further adapted to perform operations other than cage changing, which require to open the cage, specifically cleaning operations or operations on the content of the cage, such as experimenting, checking or other operations. In such a case, an apparatus with a single seat may also be particularly indicated, notwithstanding that only one seat of an apparatus with several seats may be used, or several cages may be parallelly treated on a multiple seat apparatus.